(CNN) Presidents have historically seen a bump in their approval ratings during a military crisis, but the partisanship that has gripped the country in recent years has stunted that traditional bump in the polls.

That evidence suggests President Donald Trump's approval rating -- which has lingered in the lower to mid 40s throughout his presidency -- likely won't see too much of a change in the wake of the killing of Iranian Gen. Qasem Soleimani and the Islamic Republic's retaliatory strike on Iraqi bases housing US troops this week.

Last week, Trump ordered a strike that killed Soleimani, the leader of Iran's Islamic Revolutionary Guard elite Quds force, which was followed by a strike from Iran against Iraqi bases housing US troops. In a speech to the nation on Wednesday, the President announced new sanctions "until Iran changes its behavior."

Traditionally, political observers could expect such events to inspire a "rally around the flag" polling bump for the person in the Oval Office. But, Trump's extremely steady approval rating and a growing partisanship in the US may prove stronger than that "rally around the flag" bump.

During Operation Desert Storm in the Gulf War of early 1991, President George H.W. Bush deployed troops to Saudi Arabia and began a series of air strikes on Iraq.

In an early January Gallup poll , 58% of Americans approved of the job the elder Bush was doing as president. That number rose to 82% in late January after the strike. That bump represented one of the strongest boosts in approval due to military action and national pride. Bush's highest approval rating in his presidency was 89% in late February-early March 1991 and he didn't drop back down into the 50s until much later that year.

Among Democrats, Bush rose from 42% to 77%, and also went up 14 percentage points among Republicans and 27 percentage points among independents.

His son, President George W. Bush, also saw a steep rise in his approval rating after the invasion of Iraq in March 2003. That month, his approval went from 58% in a mid-March Gallup poll to 71% in late March, after the US invaded Iraq on March 19, 2003. Approval among Democrats rose from 31% to 48% that month, remained steady among Republicans (in the mid-90s) and jumped from 50% to 69% among independents.

More than half of Americans said at the time that the situation in Iraq was worth going to war over, according to a Gallup/CNN/USA Today poll conducted in January 2003, while 42% said it wasn't worth going to war.

But in the early part of the last decade, Trump's predecessor Barack Obama didn't see similar gains in his approval rating after military strikes.

Obama's presidency was highlighted -- in the national security field -- by the killing of al Qaeda leader Osama bin Laden in 2011 and air strikes in Syria in 2014.

His approval rating in 2011 was bumped after bin Laden's death, up from 44% in late April to 51% in May, a much smaller rise than previous presidents saw after major military action. That moment didn't result in Obama's highest approval rating, and the small boost didn't last long -- he was back to 43% by June.

In late September 2014, Obama ordered the military to begin strikes against ISIS targets in Syria, an action well-received by most of the public (73% favored the strikes, according to a September 2014 CNN/ORC poll ). But his approval rating barely moved. The Gallup trendline for Obama's approval rating shows basically no change in that time frame.

On December 16, 1998, President Bill Clinton launched days of airstrikes against Iraq, causing Republicans to delay his impeachment in the House by a week. Clinton's launch against Iraq shows many similarities to Trump's due to the impending impeachment trials for the presidents.

Clinton did receive a burst in approval (from 63% before the airstrikes to 73% the week after), but was back to the same levels of approval by February 1999.

In March 1999, when the US (as part of NATO) bombed Kosovo, Clinton's approval rating fluctuated a bit, but no significant jumps like the earlier 10 percentage points occurred.

Trump's recent action in Iran -- striking and killing Soleimani and then deciding not to respond to Iran's missile strike with further military action -- is the latest flashpoint in his presidency. So far, Trump's presidency has been remarkable for the inability of events to affect his approval rating.

His highest high, according to Gallup tracking, was 46% in April 2019 and his lowest was 35% on a few occasions in late 2017. It's rare for a president to only have an 11 percentage point spread between his low and high.

Trump has previously ordered airstrikes in Syria and they hardly affected his approval rating.

In 2017 and 2018, the Trump administration enacted a series of airstrikes in Syria. Both occurred in April and neither moved Trump's approval more than a few percentage points in either direction. In 2017, his approval moved from 38% to 40% after they began and in 2018, from 39% to 42%.

A likely reason for the stagnation is the growing partisan divide in the US. Parties no longer agree on "basic facts," and see the other group as more different and disliked than their own group. This change began during Obama's presidency, when Gallup's polls showed fewer Republicans changing their support depending on his actions. During the Bush eras, Democrats approval of the president varied more.

It's unlikely that Trump's approval will move more than a few points -- his last approval in December at 45%, higher than usual -- but it could tick up past his highest point.