The reportedly acrimonious telephone conversation between Australia Prime Minister Malcolm Turnbull and United States President Donald Trump is extremely unfortunate, both because of current tensions in the region and the close historically rooted alliance between our two nations. Australia is crucial to U.S. defense and security in Asia, and beyond.

China represents an important, growing challenge to both nations. While attention tends to focus on the economic dimensions of China’s influence, that great power’s military expansion is also of concern, which introduces the generally under-reported role of Australia. In 2011, President Barack Obama addressed a session of the Australian parliament, and then-Prime Minister Julia Gillard announced an agreement to station U.S. Marines in that country.

During confirmation hearings in the U.S. Senate, Secretary of State Rex Tillerson stated explicitly that the U.S. should oppose China’s access to disputed reefs and islands in the South China Sea. Beijing has an aggressively expanding presence in the area. China has stated any sea blockade would be an act of war.

In this tense context, Australia remains a vital U.S. ally. ANZUS, the Australia-New Zealand-U.S. security alliance, was dramatically re-energized by the terrorist attacks of 9/11. Australians were targets in the 2002 terrorist bombings in Bali. In 2004, the Australian Embassy in Jakarta was attacked.

The American-Australian special relationship was forged in the crucible of World War II. In that war, the enormous Japanese military drive south was finally blunted just short of Australia. Knowledgeable jungle-savvy Australian troops provided vital support to generally inexperienced Americans.

The Vietnam War led to strengthening the Australia-United States partnership even while straining U.S. relations with Britain and other allies. A total of 50,000 Australian military personnel served in Vietnam; 520 were killed and 2,400 wounded. Reflecting these pressures, Australia reintroduced military conscription in 1964.

In October 1966, Lyndon B. Johnson became the first U.S. president to visit Australia, underscoring cooperation with Prime Minister Harold Holt. This characteristically dramatic LBJ expedition was undertaken to cast the Vietnam War in global terms.

Australian forces gained valuable guerrilla war experience during the Malaya Emergency from 1948 to 1960 fighting the Malayan National Liberation Army. The insurgency was finally suppressed, confirming the value of long-term patience in employing sustained, carefully directed military force.

President Richard M. Nixon and national security adviser Henry Kissinger tried to apply Malaya insights to Vietnam. Sir Robert Thompson, a highly respected British guerrilla warfare expert, was consulted and provided an encouraging estimate of the prospects of the South Vietnamese military.

General Creighton Abrams, after succeeding General William Westmoreland as Vietnam commander, redirected U.S. forces away from massive search-and-destroy operations to small unit actions, reflecting the strategy successfully employed in Malaya. The war strengthened ties between Australia and the U.S. among military and civilian government professionals.

The Afghanistan insurgency is somewhat similar to Malaya and Vietnam. David Kilcullen, a retired Australian army officer, is influential in American security circles. Australians also do humanitarian work in Pakistan and elsewhere.

Australia provides an important bridge between developed and developing nations, reflecting historical legacies as well as geography. The nation’s economy has been greatly aided by proximity to China.

Australia along with Britain and New Zealand provides deep Asia diplomatic as well as military experience. Canberra has also indicated interest in a trade deal with London following Britain’s departure from the European Union. We need Australia now — more than ever.

— Arthur I. Cyr is Clausen Distinguished Professor at Carthage College and author of ‘After the Cold War.’ Contact at acyr@carthage.edu.