Hezbollah’s leader Hassan Nasrallah stepped up the war of words with Israel on Friday, threatening that thousands of Shi’ite militia fighters could join forces with Hezbollah in a future war with Israel.

“This could open the way for thousands, even hundreds of thousands of fighters from all over the Arab and Islamic world to participate – from Iraq, Yemen, Iran, Afghanistan and Pakistan,” he said in a televised speech.

Nasrallah’s comments follow weeks of rising tension between the Israeli government and Hezbollah, as fears grow that Israel might find itself drawn into another costly conflict with Iran’s notorious Lebanese proxy. When war breaks out – and it seems more a question of when, not if –  Israel will fight a very different enemy than the one it confronted in the summer of 2006.

Hezbollah has suffered heavy casualties fighting in Syria since 2012. But it has also acquired a new set of skills and military infrastructure, which morphed the group into a much more formidable foe. Hezbollah no longer is a state-within-a-state; Hezbollah is the de facto ruler of Lebanon. And through its activities abroad, the group has learned how to fight conventional wars and has significantly expanded its rocket stockpiles.

For now, the volatile northern border is quiet but winds of war are blowing in Israel’s direction. Under the cover of charitable work, Hezbollah has reportedly constructed observation posts near the Israeli line – operated by the environmental group Green Without Borders – in what appears to be an attempt to restore the situation along the border to what it was before the 2006 war. Hezbollah used strategic positions to keep track of IDF activity and gathered intelligence that helped the group carry out the abduction of two Israeli soldiers, the incident that triggered the war.

After an event that took place in May, the Israeli government decided to take preventive steps and invested in a new border fence, similar to the “smart fences” found along the borders with Egypt, Jordan and Gaza.  A Lebanese man had walked several kilometers inside Israeli territory, before he was apprehended in the town of Kiryat Shmona – a taste of what might come with Hezbollah ready to strike at the gates.

Long gone are the days when Israel had hopes for a peaceful and democratic Lebanon. The Christian and Sunni opposition is fractured and ineffective, leaving Hezbollah with more power and legitimacy than ever. And in addition of having a firm grip on Lebanese politics, Hezbollah has also taken the lead in shaping the country’s foreign policy.

Hezbollah is an integral part of the Shi’ite crescent, spearheaded by Iran, encompassing Syria, Iraq, Lebanon and, as of late, Yemen. Hezbollah has long operated abroad at the behest of its sponsor and strategic partner in Tehran. Iran transfers weapons and missiles and provides training and technology to the group. Iran is also building facilities to produce precision weapons and advanced rockets inside Lebanon, a development which Israel says it will not tolerate.

Iran, which is funding Hezbollah with at least $100 million per year, is fighting in Syria on behalf of the murderous Assad regime and relies heavily on the support of Hezbollah as a force on the ground. Other allies include the Iraqi-based Shi’ite militia Hashd al-Shaabi (also known as the Popular Mobilization Units), which recently reached a strategic corridor along the Iraq-Syrian border near Sinjar. With the Syrian regime simultaneously advancing along the other side of the fence near al-Tanf, the two Iranian-backed parties could  physically link the territory to form a corridor between Iran and Lebanon, through northern Iraq and Syria.

This, however, is not the only development that is making Israel nervous. While it is true that the war in Syria has claimed many of Hezbollah’s fighters, the group has managed to significantly increase its rocket stockpiles. When war broke out in 2006, estimates suggest Hezbollah had approximately 13,000 short-range rockets. Now it could have as many as 150,000, including weapons with much greater range and precision.

Iron Dome, Israel’s major defense system, proved successful at intercepting missiles from Gaza, but there is fear that Hezbollah’s new generation of rockets could overwhelm the system. Iron Dome is not equipped for hundreds of missiles launched simultaneously, meaning rockets from Lebanon could potentially hit cities in Israel’s heartland.

For several years now, Hezbollah has been transfixed on the war in Syria. But with the tide turning in favor of the Assad regime and Iran’s ascendancy in the region, attacks on Israel will once more feature highly on the group’s agenda. In such a climate, Hezbollah’s war of words could quickly transform into words of war.

Julie Lenarz is a Senior Fellow at The Israel Project and the Executive Director of the London-based think-tank Human Security Centre. She tweets @MsJulieLenarz