Is Jordan about to invade Syria? That was the speculation following the unprecedentedly large "Eager Lion" joint military exercise with the US and other international partners in Amman in May.

This, alongside an exchange of insults with Damascus and increased tension between US and Iranian proxies near Syria's al-Tanf, prompted speculation that, as part of Trump's more aggressive line with Bashar al-Assad and Iran, his Hashemite ally might open a new front in Syria's south.

Jordan has played a smarter hand than most of Syria's neighbours to insulate itself from the fall out of the six-year conflict

Jordan was swift to deny this, and with good reason: it would mean the total abandonment of its cautious policy towards the Syrian civil war.

Jordan has played a smarter hand than most of Syria's neighbours to insulate itself from the six-year conflict's fall out. The four neighbouring states with open borders before the war - Turkey, Jordan, Iraq and Lebanon - all received vast numbers of refugees and saw trade plummet, but violence has spilt over too.

Iraq and Turkey have seen battles with the Islamic State (IS) group and the Kurdistan Workers' Party (PKK) re-open. Lebanon has seen sporadic fighting along its borderlands.

In contrast, while Jordan has faced IS terror attacks, it has largely been spared the fighting seen elsewhere.

Tight border control

Local conditions differ along the Syrian regions that neighbour each state, but how porous the border has been has impacted the extent of spill over.

Iraq and Lebanon are weak states whose militaries struggled to prevent actors from within and without traversing their borders. Turkey opted to back armed anti-Assad forces early in the war, turning a blind eye or even actively encouraging fighters crossing into Syria. Many of these would go on to join IS or Jabhat al-Nusra, while the PKK's Syrian arm, the PYD, also benefitted.

In contrast, Jordan, while also backing the opposition, controlled its border more tightly and tried harder to vet those that did cross. Partly as a result, six years on, moderate rebel forces remain relatively strong in southern Syria while in the north, they have largely been subordinated to radical groups like IS and al-Qaeda.

In contrast to Turkey, which saw the Syrian civil war and the Arab spring as an opportunity to extend Ankara's regional influence, Jordan's King Abdullah viewed both in terms of survival. The past six years has seen Jordan carefully balance its security and domestic concerns with the demands of its key international allies, many of whom were fervently anti-Assad.

In terms of security threats from Syria, Jordan fears radical jihadists like those from IS and al-Qaeda. As the tide turns against IS in Syria, Amman is anxious that the remnants of the "caliphate" don’t turn their attention to Jordan via home grown sympathisers. Late last year, IS claimed its first attack in Jordan when 10 people were gunned down in Kerak, while six soldiers were killed in a border attack the previous summer.

Jordan, unsurprisingly, joined the US anti-IS coalition as soon as it was formed in 2014 and, unlike the Gulf states who later reduced their role, remains active. Unlike Turkey, which was slow to recognise the threat from IS, it was fear of jihadists ready to attack Jordan, among the rebels that motivated the country’s much tighter border policy from the very beginning.

Aid leverage

The conflict has prompted further domestic concerns. Jordan has received 1.4 million Syrian refugees, 660,000 registered with the United Nations, many from poor parts of Syria, straining resources and competing for work with locals. This was worsened by the closure of Syrian and Iraqi trade routes, contributing to Jordan's highest unemployment rates in decades.

However, Jordan has tried to turn the situation to its advantage. Long a beneficiary of "location rent" from allies in the US and Gulf, Jordan has used the refugees' presence to seek greater international aid.

For years, it demanded that any funds received for Syrians must be matched with development aid that would benefit Jordanians. More recently, in 2016, a major donor conference brought $1.7bn in pledges, conditional on Jordan granting more work permits to its refugees.

While this had mixed results, Amman thus far seems to have successfully leveraged the refugee crisis to its advantage rather than be overwhelmed by it.

A careful dance

Perhaps the greatest challenge from Syria's war has been managing Jordan's international ties. Jordan is firmly in the US and Saudi Arabian regional camp, depending on both economically and militarily, and joined their calls for Assad to stand down in 2011 – a sentiment conveniently shared by the Jordanian public.

However, these allies pulled Amman in different directions. Barack Obama shared King Abdullah's caution about arming Syria's rebels, but Saudi Arabia pressured Jordan to do more.

The result was a careful dance from Jordan, allowing weapons and training over the border to vetted, mostly tribal, rebels through the CIA-led Military Operations Center in Amman, but resisting any efforts to directly intervene or open the border more.

Now under Donald Trump, the Saudis and the White House seem more aligned, with Iran the main threat, and the US wants to use Jordan as a base to frustrate Tehran’s plans along the Syrian border.

However, while Jordan has no desire to see Iranian proxies along its border, and knows it must maintain close ties with both Riyadh and Washington to survive, it remains unlikely to yield to any untenable demands.

Israeli-Jordanian cooperation has reached new heights during the Syrian conflict. This has involved intelligence sharing on militant groups, Assad, and Hezbollah, and a joint show of air power to deter Russian jets from southern Syria.

However, Jordan has complained that Israel seems to be ignoring and may even have aided a Jabhat al-Nusra pocket emerging near the occupied Golan Heights. While Israel may see these jihadists as a counterweight to Hezbollah, Amman sees a threat.

Russia meanwhile, while Assad's ally and the US' enemy, retains more ambiguous ties to Amman. Relations have improved in recent years, including strengthened trade and defence ties. Pragmatically, with Vladimir Putin intervening on Assad's side, Amman knows Moscow will be the power broker in any peace agreement, while Russia knows Jordan will be key for any deal to hold in the south.

Russia invited Jordan to attend the Astana ceasefire talks and has urged the border zone to be one of its four proposed "de-escalation" zones. Characteristically, in pursuit of Jordan’s security, Abdullah urged Moscow and Washington to reach an agreement on this.

Insulation and crackdowns

Despite seeing its neighbour to the north consumed by civil war, the Jordanian government has managed to insulate itself better than Syria's other neighbours thus far. Survival has required a clever game of balancing essential international relationships while never losing sight of its core security and domestic priorities.

The Hashemites have successfully managed a regional crisis in Syria, and are unlikely to shift this cautious approach unless it suddenly impacts the regime’s survival

This has not come without a cost, however, and Syria's civil war has coincided with a crackdown at home. In March, 15 alleged terrorists were executed – unusually harsh for Jordan – while a reform movement that emerged in 2011 has been repressed.

As through much of Jordan's history, the Hashemites have successfully managed a regional crisis in Syria, and are unlikely to shift this cautious approach unless it suddenly impacts the regime's survival.

However, as has also been common in Jordanian history, this has come alongside a willingness to crack down at home, with its key location protecting Abdullah from Western criticism.

- Christopher Phillips is Senior Lecturer at Queen Mary, University of London and Associate Fellow at Chatham House. His latest book, The Battle for Syria: International Rivalry in the new Middle East is on sale now.

The views expressed in this article belong to the author and do not necessarily reflect the editorial policy of Middle East Eye.

Photo: In January 2016, Jordan’s King Abdullah II celebrates the centenary of the Arab Revolt against the region’s ruling Ottoman Turks (AFP).

This article is available in French on Middle East Eye French edition.