The United States doesn’t declare wars, it escalates them, sinking deeper into tragic and costly ventures where each step justifies the next. In Iraq and Syria, the familiar mission creep has begun. President Obama has expanded a bombing campaign, doubled the U.S. troop level to 3,100 and requested $5 billion in new funding to fight Islamic State insurgents.

The latest U.S. war in the Middle East looks increasingly like another long-term commitment. How many years, no one knows. Hawkish members of Congress are demanding to intensify the battle. The president should reject their counsel and halt the return to war in a nation that has seen too much U.S.-inflicted suffering.

In a haunting echo of Vietnam, the vanguard of American troops in Iraq are called advisers. Where the advice led 50 years ago teaches a bitter lesson. The mission started creeping. The war took on a ghastly life of its own. Eventually half a million American men were fighting in Southeast Asia.

We might think nothing like this could happen again. But the deterrent effect of past wars’ failures has a short lifespan. The slope gets slippery. Victory eludes, charges of weakness rise, and the pressure to escalate grows. Voices for peace need to be heard at times like these.

Mennonite Central Committee is one of these voices. In an Oct. 10 letter to the president and members of Congress, J Ron Byler, executive director of MCC U.S., expressed “deep concern” over U.S. airstrikes against Islamic State militants. “We urge the U.S. government instead to address the political and social grievances within Iraq and Syria, engage in sustained and energetic regional diplomacy, address humanitarian needs and support those seeking to build relationships of peace and reconciliation within the region,” Byler wrote.

All who support MCC are part of a vital Christian witness for peace in the Middle East. Byler notes that “since the Syrian crisis began in March of 2011, MCC has allocated more than $19.8 million in emergency food, shelter, nonfood items, education, peacebuilding and disaster response training in Syria, Jordan and Lebanon.” In the last few months, MCC has given $200,000 in aid to families displaced by fighting in northern Iraq.

MCC is asking its supporters to urge Congress to oppose the use of military force in Iraq and Syria. This may be a faint hope. But at the very least, Congress ought to fulfill its duty and vote on whether to authorize the war and place strict limits on it. Ceding authority to the president avoids the debate that is morally necessary and legally required before dropping bombs and taking lives.

The human cost of war belongs at the center of the debate. The website antiwar.com documents the daily death toll of combatants and civilians. On Oct. 6, according to Iraqi media, a U.S. air attack intended for a building that housed Islamic State fighters struck a marketplace and apartments in the town of Hit, Iraq. Local residents said the bombs killed at least 18 civilians and wounded many more. Pentagon officials denied the report of civilian deaths, as they usually do.