After Iran hit Iraqi-military bases that housed US troops in retaliation of the death of their top general, the US President Donald Trump announced new sanctions against the crumbling Iran’s economy and officials. For now, it was an end to a possible military confrontation between the two countries, but it seems that both go to a shadow war across the region, as they did for 40 years.

The Middle Eastern region has been largely the main shadow battleground between the United States and Iran and Iranian proxy forces. The sandwiched country between the Middle East and South Asia, Afghanistan may turn into another shadow battleground between the United States and Iran, amid peace efforts to end 18-year long insurgency in the country.

The United States has been the strategic partner of Afghanistan for 18 years and helped the country to build national institutions from the ashes of civil war in the 1990s, from the military to judicial. On the other hand, Afghanistan shares borders and long complicated and extensive political, social, and economic ties with Iran.

“The government of the Islamic Republic of Afghanistan assures the people and its neighbors that, according to the security agreement with the United States, the territory of Afghanistan in no circumstances will be used against another country,” said President Ashraf Ghani of Afghanistan in a statement days between the death of top Iranian general and missile strikes into Iraqi military bases.

As the tension between the United States and Iran drags on, the US peace envoy Zalmay Khalilzad met in silence with the Taliban representatives, discussing reduction of violence and ceasefire to reach an agreement for peace in Afghanistan and withdrawal of US troops. Afghans fear that US-Iran tension hurt the chance of peace for Afghanistan.

“Iran has refused to join the regional and international consensus for peace, and is, in fact, actively working to under the peace process by continuing its long global effort to support militant groups there [in Afghanistan],” said US Secretary of State Mike Pompeo at a State Department news conference. “Taliban’s entanglement in Iran’s dirty work will only harm the Afghanistan peace process.”

Over 18 years that the United States poured in millions of dollars and deployed nearly a million US troops in Afghanistan, while Iran cultivates connection with elements within the Taliban group. US and Afghan officials accused Iran of arming the Taliban group, a charge Iran denied. In addition, Iran recruited, trained, and paid thousands of Afghan Shiites to fight for Iran in the Syrian war under the division of Fatimyoun.

The influence of Iran in Afghanistan came to light when US killed Qaseem Suleimani, head of Iran’s Quds force. Ex-President Hamid Karzai, who was saved by US Special Forces for years and was backed in power for 13 years, condemned the strike against Suleimani and named him as a “man of dignity.” Former National Security Advisor Hanif Atmar, the official who signed the strategic security agreement with the United States, called Suleimani as a “martyr.”

Photos of Afghan ambassador to Iran circulated on social media showing him in the funeral of Suleimani in Tehran. At least two Afghan politicians were seen at the funeral of Suleimani in Tehran. Abdullah Abdullah, the chief executive of the United States backed and brokered government, went to the Iranian embassy in Kabul to pay his tribute and to sign a memorial book on Suleimani.

“We expect an escalation of tech-Mil support [for the Taliban] by the Iranian regime plus the potential deployment of Fatimyun bridge on the Afghan battlefields this coming fight season [spring is usually the start of insurgency season],” said Tamim Asey, former deputy for Afghan defense minister. “Time and this coming fighting season will tell.”

The New York Times reported that the United States “air assets in Afghanistan have repeatedly come up in discussions over a potential response to Iran, though the top United States commander in Afghanistan has urged caution about such plans.”

Turning Afghanistan into a battlefield might be too costly for both the United States and Iran. The United States have already been fighting an endemic insurgency in the country with the Afghan government is entangled with widespread combat with the Taliban group across the country. Iran, meanwhile, fights and supports proxy forces across the Middle East, from Lebanon to Yemen.

“If Iran escalates its proxy war through Taliban and Fatimyun, they will be the biggest losers themselves,” said Tamim Asey. “It essentially amounts to shooting themselves in the front i.e. opening two fronts in both western [Iraq] and eastern borders [Afghanistan].”