Yesterday, U.S. Attorney General William Barr accused Apple of failing to cooperate with the iPhone maker in unlocking the phone used by the perpetrators in the December terrorist attacks. And now President Trump is stepping up the pressure on Apple as well.

The president used his favorite medium, Twitter, to criticize Apple, posting a tweet this evening (January 14) calling on the tech giant to "step up to the plate and help our great country."

The tweet is in line with President Trump's transactional view of politics and policymaking. The Trump administration has spared Apple from many of the tariffs imposed on its goods as part of the ongoing trade war with China. Now is the time for Cupertino to return the favor by unlocking the phones of "murderers, drug dealers, and other violent criminals," the president claimed in a tweet.

Apple has not yet responded to our request for comment on President Trump's Twitter-based message, but the two iPhones used by Mohamed Saeed al-Shamrani, the gunman who killed three people and wounded eight others at Pensacola Naval Air Station on December 6 The company issued a lengthy statement regarding Barr's January 13 criticism of how Apple responded to a request to unlock the

Apple denied Barr's claim that it had not provided "substantial assistance" and said that it had and would continue to respond thoroughly to government requests.

"We continue to work with the FBI and our engineering team recently received a call to provide additional technical assistance," Apple told Tom's Guide.

Apple and the government are at odds over the creation of so-called "backdoors" to encrypted messages. Government investigators have called for such tools, but Apple has pointed out that they would compromise the privacy and security of all users.Four years ago, Apple refused to unlock the iPhone used by the shooter in the 2015 San Bernardino, Calif. and posted an open letter explaining the need to keep personal information encrypted.

Al-Shamrani used an iPhone 5 and an iPhone 7. Both of these devices are old enough that security experts believe they can be unlocked without Apple's help using third-party tools.

Nevertheless, the Trump administration is clearly trying to increase public pressure, which may put Tim Cook in an awkward position. The Apple CEO has publicly courted President Trump, inviting him to tour the Texas facility where the Mac Pro is assembled. (Cook has also visited the school with Ivanka Trump, the president's daughter and White House advisor, to showcase his commitment to STEM.

As a result, policy decisions favorable to Apple have been made by the Trump administration, particularly in the area of tariffs. The President has now hinted that he wants something in return from Apple, and it will be interesting to see how the company reacts.